Drawing of metal tubing



y 1967 s. H. RICHARDS 3,330,146

DRAWING OF METAL TUBING Filed Oct. 13, 1964 2 Sheets-Sheet 1 Co I F I l LA O f 2-: l

Inventor SAMUEL HUGH RICHARDS Attorneys y 11, 1967 s. H RICHARDS 3,330,146

DRAWING OF METAL TUBING Filed Oct. 13, 1964 2 Sheets-Sheet 2 5 8 C) C) C) 5 8 C) G 4 O C) Inventor SAMUEL HUGH RICHARDS A tlorneys United States Patent 3,330,146 DRAWING OF METAL TUBING Samuel Hugh Richards, Crook, Durham, England, assignor to Marshall Richards Machine Company Limited, Durham, England, a British company Filed Oct. 13, 1964, Ser. No. 403,607 Claims priority, application Great Britain, Oct. 14, 1963, 40,371/63 4 Claims. (Cl. 72-362) This invention relates to an improved method of drawing metal tubing and also to an improved tube drawing machine.

In the drawing of metal tubing, there are advantages which result from operating with coils of tubing which are as long as possible since, the longer a coil of tubing is, the smaller the proportion of the total drawing time of a coil, is taken up by the coil end preparation (i.e. lubricating inserting the floating plug into, and pointing the tube end, threading the pointed end through the die and securing the pointed end to the drawing block). In general therefore, for economical operation of a tube drawing machine, we prefer to design the machine so that we can employ coils whose size is limited only by considerations of the ease of handling.

In the case of coils of large bore diameter the acceptable limit to ease of handling is normally set by the overall weight of the coil and in the case of coils of small bore diameter the acceptable limit is often set by the problems involved in controlling the many turns of tubing in a long coil without running the risk of tangling the turns or otherwise damaging the tubing.

Specifically, this invention relates to an improved tube drawing machine for tubing of small bore diameter where, owing to the length of tubing employed in the coils, there is a need for careful control of the coils fed on to and received from the drawing block.

One object of the present invention is to facilitate the drawing of long coils of small bore tubing without running the risk of tangling the coils or otherwise damaging the tubing.

A further object of the present invention is to enable the safe handling of longer coils of small bore tubing than has hitherto been possible and thereby to provide enhanced economic operation of a tube-drawing machine.

A still further object of the present invention is to enable easy batch operation of a tube drawing machine whereby a plurality of long coils of tubing can be passed successively through a graded series of drawing dies, each coil being securely supported on the machine both during and between drawing operations.

A still further object of the present invention is to allow a tube drawing machine for small bore tubing to be operated so that substantially the entire operating time of the machine is utilised for tube-drawing, coil-end preparation on the next coil to be drawn being carried out while the machine is engaged in drawing the previous coil.

According to one feature of this invention, a method of drawing metal tubing comprises leading a coil of tubing from a rotating paying-out spool through a drawing die, laying the tubing, as it leaves the die, in a helix on the surface of a rotating drawing block and collecting the tubing as it leaves the block on a rotating take-up spool, said take-up spool subsequently serving as the paying-out spool when, in a later operation the tubing is drawn in the opposite direction through a further die.

Conveniently the helix of tubing on the block would consist of some 6 to 8 turns. Preferably the speeds of rotation of the two spools and the block are controlled so that tension is maintained in the tubing in the length 3,339,146 Patented July 11, 1967 ICC extending between the paying-out spool and the die and in the length extending between the block and the takeup spool.

According to a further feature of the present invention, a tube drawing machine comprises a rotatable drawing block having a tube-engaging peripheral surface which is symmetrical about the axis of rotation of the block and at least two spaced-apart spool-supporting members located on each side of a vertical plane through the axis of rotation of the block, each supporting member being adapted to rotatably support a spool of tubing or an empty spool on which tubing may be wound, the axes of rotation of spools mounted on the spool supporting members each being disposed perpendicular to lines which are normal to said vertical plane, and two die boxes, one to be employed when tube is being drawn from spools on one side of the block and the other to be employed when tube is being drawn from spools on the other side of the block.

There are advantages which result from making the various spool-supporting members movable bodily in a direction parallel with the axis of rotation of a spool mounted thereon, since in this Way a spool not actually employed in a darwing operation may be withdrawn from the tubing passing to or from the block.

One tube drawing machine in accordance with the invention will now be described, by way of example, with reference to the accompanying schematic drawings, in which:

FIGURE 1 is a plan of the machine,

FIGURE 2 is an end elevation of the machine of FIGURE 1, and

FIGURE 3 are schematic representations of the machine of FIGURES 1 and 2 illustrating a preferred mode of operation.

Referring to FIGURE 1, the machine comprises a rotatable drawing block 1 having a tube-engaging peripheral surface which is flanged at one end (marked 2 in the drawing). The block 1 is driven by a motor 3 and can be driven in either clockwise or anti-clockwise direction.

Mounted to the left of the block are two spaced-apart spool-supporting members 5 and 6 and mounted to the right of the block are two further spaced-apart spoolsupporting members 7 and 8. Each spool-supporting member is shown with a spool attached (Which for convenience has been given the same reference numeral in FIG- URE 3 as the associated supporting member), the respective spools being rotatable clockwise, or anti-clockwise, about axes which are parallel to the axis of rotation of the block. When spools 5 and 6 rotate in a clockwise direction they are serving as take-up spools and when they rotate in an anti-clockwise direction they are serving as paying-out spools. With spools 7 and 8 the situation is reversed so that clockwise rotation represents paying-out and anti-clockwise rotation taking-up. The support shaft 12 of each supporting member is drivable in the taking-up direction by a torque motor 13, and in the paying-out direction is partially braked by a slip clutch (not shown).

The spool-supporting members are each attached to hydraulic rams 14 which enable the members to be moved bodily in a direction parallel to the axis of rotation of the attached spool for a reason which will become clear hereinafter. Further, each shaft 12 is reciprocable in its axial direction in known manner to allow even layering of tubing on a spool during take-up.

The block 1 is provided with a pulling-in dog 9 which can pivot through more than to receive tubing from spools 5 and 6 or from spools 7 and 8. Associated with the block 1 are two die boxes 10 and 11, each die box being movable in a direction parallel to the axis of rotation of the block by an hydraulic ram 15.

The machine illustrated would, most advantageously,

be used in the following manner:

Coils of tubing from a conventional tube block would be employed and would be fed to the machine from a swift.

After lubricating, inserting a floating plug and poin ing, the end of a coil of tubing resting on a' convenbox is drawn, 'by ram 15, back towards the flanged end 2. The rate at which the box 10 moves is determined on the basis of the external diameter of the tubing and the speed of rotation of the block and is set so that the tubing forms a smooth helix on the tube block. When the tubing reaches the inclined surface of the flanged end 2 (usually after about 6 or 8 turns have been drawn on to the block), the block is stopped and the end of tubing in the dog 9 is released (possibly by being sheared automatically after a press-button operation) and is taken by .hand to one of the spools 7 and 8 (the block .being inched round as the tubing is payed ofl). The end of the tubing is then secured to the spool and the block and spool rotated. The torque motor 13 drives the spool at a speed commensurate with the speed of rotation of the block 1 (in a manner well known in the wire and tube drawing arts) so that some tension is maintained in the tubing extending between the spool and the block.

During the drawing operation, the die box 10 remains in the position shown in FIGURE 1, the tubing being fed on to the block 1 close to the flanged end 2, successive turns of tubing urging the earlier turns towards the free end and the take-off point.

A number of pressure rollers 16 (see FIG. 2.) bear down on the tubing on the blockto keep it in contact with the tube-engaging surface. Such rollers are preferably driven via a slipping connection, so that they endeavour to run faster than if under normal frictional contact. The rollers also serve to contain the tubing on the block during the threading of tubing to the spool 7 or 8 and ultimately, after the end of the tubing passes through the die box.

The take-up spool and block now draw thetubing off the swift on to the machine. The spindle 12 is reciprocated axially during spooling to ensure that the tubing is evenly layered on the spool. The operation described indicates how one coil of tubing may be fed on to the machine and We will. now describe the preferred mode of operation of the machine assuming three of the four sp'ools support a coil of tubing.

Let us assume spool 7 is empty and that tubing on spools 5, 6 and 8 requires to be drawn through the same given-size die. Die boxes 10 and 11 would be fitted with a die of this size and the prepared end of tubing from spool 6 would be led through the die in die box 10 passed several times round the block 1 as the die box 10 is moved back towards the flanged end 2 (i.e., in the manner just described) to form a helix on the block.

The end of ,the tubing on the block is then taken off 7 and secured to spool 7. With the block 1 rotating clockwise drawing would proceed with spool 6 rotating anticlockwise and serving as the paying-out spool and spool- 7 rotating anticlockwise and serving as the take-up spool. While this drawing operation is proceeding, the end of the coil of tubing on spool 8 is being prepared and fed through the die in die box 11' so that as soon as the block 1 is free of tubing, the dog 9 can be pivoted round to receive the tubing from spool 8 and draw it on to the block. By traversing die box 11 towards the flanged end 2 a few turns are laid in a' helix on the block, the end of the tubing then being removed from the dog 9 V 4 V V V andled to the emptied spool 6. Drawing now proceeds with spool 8 rotating clockwise and serving asrthe paying-outspool block 1 rotating anticlockwise and spool 6 rotating clockwise and serving" as the take-up spool.= 7 While this operation proceeds, the end of tubing on spool 5 is being prepared and fed through the die in die box 10. FIGURE 3 shows how the remainder of the sequence 7 tangling the turns and with very little risk of the tubing 7 becoming damaged.

Although the specific machine illustrated has a drawing block with a horizontal axis and two spool-supporting members on each side of the block, these should not be considered as limitations on the scope of the invention, and vertical or otherwise oriented blocks together with more than four spool-supporting members-could be used.

One or more of the spools maybe of the collapsing type enabling coils to be strapped with wire and'removed bodily therefrom when a full sequence of operations on that coil has been completed.

The machine illustrated employs a single dog 9 which can be pivoted through an angle of greater than 180'. It will be appreciated that in place of a single dog 9, two dogs could be employed, either mounted with their pivoting axes coaxial or with their pivoting axes parallel, one dog being employed with each die box.

I claim:

1'. A tube drawing machine comprising a rotatable drawing block having a tube-engaging circular cylindrical surface, a pulling-in dog pivotally secured to the block about an axis parallel to the axis of rotation of the block and capable of pivoting through an angle greater than 180 and a motor for driving the block in both clockwise and anticlockwise directions; two tube-drawing dies, one mounted on each side of a vertical plane through,

the rotating axis of the block and each die disposed in spaced relation to the tube-engaging surface of the block with the tube axis of each die tangential to said'surface,

and motive means for moving each die between the ends of the block in a direction parallel to the axis of the block; a first and a second group of spool supporting members each having at last two spaced-apart coil supports with one group disposed on each sideof said ver-- tical plane, a spool rotatably mounted "on each coil support, drive means for rotating each spool about an axis perpendicular to a line normal to said vertical plane, the coil spools in each group being spaced further from the block than the adjacent die, and means for moving each coil support in a direction parallel to the axis of rotation of the associated coil spool mounted thereon.

2. A tube drawing machine comprising a rotatable, drawing block having a tube-engaging circular cylindriand a second groupof spool supporting members each having at least two spaced-apart coil supports with one group disposed on each side'of said vertical plane, a

'spool rotatably mounted on each coil support, drive means for rotating each spool about an axis perpendicua V lar to a line normal to said vertical plane, the coil spools in each group being spaced further from the block than the adjacent die. V

3. A method of drawing metal tubing in which the tubing is led to one drawing die from a coil on a spool 7 attached to a first coil support forming one of a primary set of at least two coil supports located on one side of a vertical plane through the axis of rotation of a rotatable drawing block and is collected from the block as a coil on a further spool attached to a second coil support forming one of a secondary set of at least two other coil supports located on the other side of said vertical plane, said further spool subsequently serving, on reversal of the direction of rotation of the drawing block, as a supply spool for the next drawing operation through a different die, the drawn tubing then being collected from the block as a coil on a spool attached to a different one of the primary set of coil supports.

4. A method as claimed in claim 3, in which while tubing is being led from one spool to another through one die, the end of a coil of tubing next to be drawn is being prepared for drawing through the other die.

References Cited UNITED STATES PATENTS 420,165 1/ 1890 Morse 72-277 2,138,126 11/1938 Smith et al 72-289 WILLIAM W. DYER, JR., Primary Examiner. G. A. DOST, Assistant Examiner. 

1. A TUBE DRAWING MACHINE COMPRISING A ROTATABLE DRAWING BLOCK HAVING A TUBE-ENGAGING CIRCULAR CYLINDRICAL SURFACE, A PULLING-IN DOG PIVOTALLY SECURED TO THE BLOCK ABOUT AN AXIS PARALLEL TO THE AXIS OF ROTATION OF THE BLOCK AND CAPABLE OF PIVOTING THROUGH AN ANGLE GREATER THAN 180* AND A MOTOR FOR DIRVING THE BLOCK IN BOTH CLOCKWISE AND ANTICLOCKWISE DIRECTIONS; TWO TUBE-DRAWING DIES, ONE MOUNTED ON EACH SIDE OF A VERTICAL PLANE THROUGH THE ROTATING AXIS OF BLOCK AND EACH DIE DISPOSED IN SPACED RELATION TO THE TUBE-ENGAGING SURFACE OF THE BLOCK WITH THE TUBE AXIS OF EACH DIE BETWEEN THE ENDS AND MOTIVE MEANS FOR MOVING EACH DIE BETWEEN THE ENDS OF THE BLOCK IN A DIRECTION PARALLEL TO THE AXIS OF THE BLOCK; A FIRST AND A SECOND GROUP OF SPOOL SUPPORTING MEMBERS EACH HAVING AT LAST TWO SPACED-APART COIL SUPPORTS WITH ONE GROUP DISPOSED ON EACH SIDE OF SAID VERTICAL PLANE, A SPOOL ROTATABLY MOUNTED ON EACH COIL SUPPORT, DRIVE MEANS FOR ROTATING EACH SPOOL ABOUT AN AXIS PREPENDICULAR TO A LINE NORMAL TO SAID VERTICAL PLANE, THE COIL SPOOLS IN EACH GROUP BEING SPACED FURTHER FROM THE BLOCK THAN THE ADJACENT DIE, AND MEANS FOR MOVING EACH COIL SUPPORT IN A DIRECTION PARALLEL TO THE AXIS OF ROTATION OF THE ASSOCIATED COIL SPOOL MOUNTED THEREON. 